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1) The number of simultaneous jobs on external PROFIBUS DP segments and PROFINET IO systems must not exceed 32 jobs per SFC/SFB. External PROFIBUS DP segments and external PROFINET IO systems are connected via the interfaces of CPs/CMs.

Example With a CPU 414-2DP, a maximum of 48 jobs per SFC/SFB can be executed at the same time (8 each on the two PROFIBUS DP segments that are connected to the integrated interfaces of the CPU, and 32 on external PROFIBUS DP segments and PROFINET IO systems).

Rules

The following holds for S7-400 CPUs:If the data source or data sink is in a central or expansion device (CR, ER), the CPU processes the jobs synchronously. In this case the jobs are processed sequentially and you do not have to take any restrictions on the number of jobs into account.

If you are operating multiple communication partners on the PROFIBUS network, then please make sure that never more than the specified jobs are active at the same time. Here one SFB, SFC or one instruction can run several CPU cycles long.

The restrictions listed in this entry for the active jobs "RDREC" (SFB52) / "RD_REC" (SFC 59) and "WRREC" (SFB53) / "WR_REC" (SFC58) also apply to the blocks that call these SFCs, SFBs and instructions internally. These include the blocks FM_CS, PID_FM and FMCS_PID.Example: When communicating with an FM 355 (4 channels parameterized) via the FMCS_PID block, 4 read jobs are occupied.

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